Fixing device and image forming apparatus

Abstract

A fixing device includes a fixing belt and a heating section. The heating section includes a heater and a heater holding member. The heater holding member has a main body portion and a plurality of ridges. The ridges include a plurality of first ridges and a plurality of second ridges. The first ridges are disposed on a central portion of the main body portion in a width direction of the fixing belt. The second ridges are disposed in an area of the main body portion at least partially extending, in the width direction of the fixing belt, from the central portion to each of opposite ends of the main body portion. The first ridges are disposed separated at a first interval. The second ridges are disposed separated at a second interval. The first interval is smaller than the second interval.

What is claimed is: 
     
         1 . A fixing device comprising:
 a fixing belt that is endless; and   a heating section facing an inner peripheral surface of the fixing belt, wherein,   the heating section includes:
 a heater which applies heat to the fixing belt; and 
 a heater holding member which holds the heater, 
   the heater holding member has:
 a main body portion; and 
 a plurality of ridges which regulate a shape of the fixing belt, 
   the ridges protrude from the main body portion,   the ridges include:
 a plurality of first ridges disposed on a central portion of the main body portion in a width direction of the fixing belt; and 
 a plurality of second ridges disposed in an area of the main body portion at least partially extending, in the width direction of the fixing belt, from the central portion to each of opposite ends of the main body portion, 
   the first ridges are disposed separated at a first interval,   the second ridges are disposed separated at a second interval, and   the first interval is smaller than the second interval.   
     
     
         2 . The fixing device according to  claim 1 , wherein
 the ridges further include a plurality of third ridges disposed on at least one end of the main body portion in the width direction of the fixing belt,   the third ridges are disposed separated at a third interval, and   the third interval is smaller than the second interval.   
     
     
         3 . The fixing device according to  claim 1 , wherein
 the ridges further include a plurality of third ridges disposed on both ends of the main body portion in the width direction of the fixing belt,   the third ridges are disposed separated at a third interval, and   the third interval is smaller than the second interval.   
     
     
         4 . The fixing device according to  claim 1 , further comprising
 a belt holding section which rotatably holds the fixing belt, wherein   the belt holding section includes a contact section which is in contact with the fixing belt, and   a height of the ridges from the main body portion in a direction orthogonal to the width direction of the fixing belt is lower than a height of the contact section from the main body portion in the direction orthogonal to the width direction of the fixing belt.   
     
     
         5 . The fixing device according to  claim 1 , wherein
 the heater is a planar heater.   
     
     
         6 . An image forming apparatus comprising:
 the fixing device according to  claim 1 ; and   an image forming section configured to form a toner image on a recording medium, wherein   the fixing device fixes the toner image to the recording medium.